Systems and methods for acquiring calibration data usable in a pulse oximeter

ABSTRACT

The present disclosure includes a pulse oximeter attachment having an accessible memory. In one embodiment, the pulse oximeter attachment stores calibration data, such as, for example, calibration data associated with a type of a sensor, a calibration curve, or the like. The calibration data is used to calculate physiological parameters of pulsing blood.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/420,994 filed Apr. 22, 2003 now U.S. Pat. No. 7,428,432, entitled“Systems and Methods for Acquiring Calibration Data Usable In A PulseOximeter,” which is a continuation of U.S. patent application Ser. No.10/153,263, filed May 21, 2002, entitled “System And Method For AlteringA Display Mode Based On A Gravity-Responsive Sensor,” which is acontinuation of U.S. patent application Ser. No. 09/516,110, filed Mar.1, 2000, entitled “Universal/Upgrading Pulse Oximeter,” now U.S. Pat.No. 6,584,336, which is a continuation of U.S. patent application Ser.No. 09/491,175, filed Jan. 25, 2000, entitled “Universal/Upgrading PulseOximeter,” now abandoned, and application Ser. No. 09/491,175 claims thebenefit of U.S. Provisional Application No. 60/161,565, filed Oct. 26,1999, entitled “Improved Universal/Upgrading Pulse Oximeter”, andapplication Ser. No. 60/117,097, filed Jan. 25, 1999, entitled“Universal/Upgrading Pulse Oximeter.” Each of the foregoing applicationsis incorporated by reference herein.

BACKGROUND OF THE INVENTION

Oximetry is the measurement of the oxygen level status of blood. Earlydetection of low blood oxygen level is critical in the medical field,for example in critical care and surgical applications, because aninsufficient supply of oxygen can result in brain damage and death in amatter of minutes. Pulse oximetry is a widely accepted noninvasiveprocedure for measuring the oxygen saturation level of arterial blood,an indicator of oxygen supply. A pulse oximetry system consists of asensor applied to a patient, a pulse oximeter, and a patient cableconnecting the sensor and the pulse oximeter.

The pulse oximeter may be a standalone device or may be incorporated asa module or built-in portion of a multiparameter patient monitoringsystem, which also provides measurements such as blood pressure,respiratory rate and EKG. A pulse oximeter typically provides anumerical readout of the patient's oxygen saturation, a numericalreadout of pulse rate, and an audible indicator or “beep” that occurs inresponse to each pulse. In addition, the pulse oximeter may display thepatient's plethysmograph, which provides a visual display of thepatient's pulse contour and pulse rate.

SUMMARY OF THE INVENTION

FIG. 1 illustrates a prior art pulse oximeter 100 and associated sensor110. Conventionally, a pulse oximetry sensor 110 has LED emitters 112,typically one at a red wavelength and one at an infrared wavelength, anda photodiode detector 114. The sensor 110 is typically attached to anadult patient's finger or an infant patient's foot. For a finger, thesensor 110 is configured so that the emitters 112 project light throughthe fingernail and through the blood vessels and capillaries underneath.The LED emitters 112 are activated by drive signals 122 from the pulseoximeter 100. The detector 114 is positioned at the fingertip oppositethe fingernail so as to detect the LED emitted light as it emerges fromthe finger tissues. The photodiode generated signal 124 is relayed by acable to the pulse oximeter 100.

The pulse oximeter 100 determines oxygen saturation (SpO₂) by computingthe differential absorption by arterial blood of the two wavelengthsemitted by the sensor 110. The pulse oximeter 100 contains a sensorinterface 120, an SpO₂ processor 130, an instrument manager 140, adisplay 150, an audible indicator (tone generator) 160 and a keypad 170.The sensor interface 120 provides LED drive current 122 that alternatelyactivates the sensor red and IR LED emitters 112. The sensor interface120 also has input circuitry for amplification and filtering of thesignal 124 generated by the photodiode detector 114, which correspondsto the red and infrared light energy attenuated from transmissionthrough the patient tissue site. The SpO₂ processor 130 calculates aratio of detected red and infrared intensities, and an arterial oxygensaturation value is empirically determined based on that ratio. Theinstrument manager 140 provides hardware and software interfaces formanaging the display 150, audible indicator 160 and keypad 170. Thedisplay 150 shows the computed oxygen status, as described above. Theaudible indicator 160 provides the pulse beep as well as alarmsindicating desaturation events. The keypad 170 provides a user interfacefor such things as alarm thresholds, alarm enablement, and displayoptions.

Computation of SpO₂ relies on the differential light absorption ofoxygenated hemoglobin, HbO₂, and deoxygenated hemoglobin, Hb, todetermine their respective concentrations in the arterial blood.Specifically, pulse oximetry measurements are made at red and IRwavelengths chosen such that deoxygenated hemoglobin absorbs more redlight than oxygenated hemoglobin, and, conversely, oxygenated hemoglobinabsorbs more infrared light than deoxygenated hemoglobin, for example660 nm (red) and 905 nm (IR).

To distinguish between tissue absorption at the two wavelengths, the redand IR emitters 112 are provided drive current 122 so that only one isemitting light at a given time. For example, the emitters 112 may becycled on and off alternately, in sequence, with each only active for aquarter cycle and with a quarter cycle separating the active times. Thisallows for separation of red and infrared signals and removal of ambientlight levels by downstream signal processing. Because only a singledetector 114 is used, it responds to both the red and infrared emittedlight and generates a time-division-multiplexed (“modulated”) outputsignal 124. This modulated signal 124 is coupled to the input of thesensor interface 120.

In addition to the differential absorption of hemoglobin derivatives,pulse oximetry relies on the pulsatile nature of arterial blood todifferentiate hemoglobin absorption from absorption of otherconstituents in the surrounding tissues. Light absorption betweensystole and diastole varies due to the blood volume change from theinflow and outflow of arterial blood at a peripheral tissue site. Thistissue site might also comprise skin, muscle, bone, venous blood, fat,pigment, etc., each of which absorbs light. It is assumed that thebackground absorption due to these surrounding tissues is invariant andcan be ignored. Thus, blood oxygen saturation measurements are basedupon a ratio of the time-varying or AC portion of the detected red andinfrared signals with respect to the time-invariant or DC portion:RD/IR=(Red_(AC)/Red_(DC))/(IR _(AC) /IR _(DC)).

The desired SpO₂ measurement is then computed from this ratio. Therelationship between RD/IR and SpO₂ is most accurately determined bystatistical regression of experimental measurements obtained from humanvolunteers and calibrated measurements of oxygen saturation. In a pulseoximeter device, this empirical relationship can be stored as a“calibration curve” in a read-only memory (ROM) look-up table so thatSpO₂ can be directly read-out of the memory in response to input RD/IRmeasurements.

Pulse oximetry is the standard-of-care in various hospital and emergencytreatment environments. Demand has lead to pulse oximeters and sensorsproduced by a variety of manufacturers. Unfortunately, there is nostandard for either performance by, or compatibility between, pulseoximeters or sensors. As a result, sensors made by one manufacturer areunlikely to work with pulse oximeters made by another manufacturer.Further, while conventional pulse oximeters and sensors are incapable oftaking measurements on patients with poor peripheral circulation and arepartially or fully disabled by motion artifact, advanced pulse oximetersand sensors manufactured by the assignee of the present invention arefunctional under these conditions. This presents a dilemma to hospitalsand other caregivers wishing to upgrade their patient oxygenationmonitoring capabilities. They are faced with either replacing all oftheir conventional pulse oximeters, including multiparameter patientmonitoring systems, or working with potentially incompatible sensors andinferior pulse oximeters manufactured by various vendors for the pulseoximetry equipment in use oat the installation.

Hospitals and other caregivers are also plagued by the difficulty ofmonitoring patients as they are transported from one setting to another.For example, a patient transported by ambulance to a hospital emergencyroom will likely be unmonitored during the transition from ambulance tothe ER and require the removal and replacement of incompatible sensorsin the ER. A similar problem is faced within a hospital as a patient ismoved between surgery, ICU and recovery settings. Incompatibility andtransport problems are exacerbated by the prevalence of expensive andnon-portable multi-parameter patient monitoring systems having pulseoximetry modules as one measurement parameter.

The Universal/Upgrading Pulse Oximeter (UPO) according to the presentinvention is focused on solving these performance, incompatibility andtransport problems. The UPO provides a transportable pulse oximeter thatcan stay with and continuously monitor the patient as they aretransported from setting to setting. Further, the UPO provides asynthesized output that drives the sensor input of other pulseoximeters. This allows the UPO to function as a universal interface thatmatches incompatible sensors with other pulse oximeter instruments.Further, the UPO acts as an upgrade to existing pulse oximeters that areadversely affected by low tissue perfusion and motion artifact.Likewise, the UPO can drive a SpO₂ sensor input of multiparameterpatient monitoring systems, allowing the UPO to integrate into theassociated multiparameter displays, patient record keeping systems andalarm management functions.

One aspect of the present invention is a measurement apparatuscomprising a sensor, a first pulse oximeter and a waveform generator.The sensor has at least one emitter and an associated detectorconfigured to attach to a tissue site. The detector provides anintensity signal responsive to the oxygen content of arterial blood atthe tissue site. The first pulse oximeter is in communication with thedetector and computes an oxygen saturation measurement based on theintensity signal. The waveform generator is in communication with thefirst pulse oximeter and provides a waveform based on the oxygensaturation measurement. A second pulse oximeter is in communication withthe waveform generator and displays an oxygen saturation value based onthe waveform. The waveform is synthesized so that the oxygen saturationvalue is generally equivalent to the oxygen saturation measurement.

In another aspect of the present invention, a measurement apparatuscomprises a first sensor port connectable to a sensor, an upgrade port,a signal processor and a waveform generator. The upgrade port isconnectable to a second sensor port of a physiological monitoringapparatus. The signal processor is configured to compute a physiologicalmeasurement based on a signal input to the first sensor port. Thewaveform generator produces a waveform based on the physiologicalmeasurement, and the waveform is available at the upgrade port. Thewaveform is adjustable so that the physiological monitoring apparatusdisplays a value generally equivalent to the physiological measurementwhen the upgrade port is attached to the second sensor port.

Yet another aspect of the present invention is a measurement methodcomprising the steps of sensing an intensity signal responsive to theoxygen content of arterial blood at a tissue site and computing anoxygen saturation measurement based on the intensity signal. Other stepsare generating a waveform based on the oxygen saturation measurement andproviding the waveform to the sensor inputs of a pulse oximeter so thatthe pulse oximeter displays an oxygen saturation value generallyequivalent to the oxygen saturation measurement.

An additional aspect of the present invention is a measurement methodcomprising the steps of sensing a physiological signal, computing aphysiological measurement based upon the signal, and synthesizing awaveform as a function of the physiological measurement. A further stepis outputting the waveform to a sensor input of a physiologicalmonitoring apparatus. The synthesizing step is performed so that themeasurement apparatus displays a value corresponding to thephysiological measurement.

A further aspect of the present invention is a measurement apparatuscomprising a first pulse oximeter for making an oxygen saturationmeasurement and a pulse rate measurement based upon an intensity signalderived from a tissue site. Also included is a waveform generation meansfor creating a signal based upon the oxygen saturation measurement andthe pulse rate measurement. In addition, there is a communication meansfor transmitting the signal to a second pulse oximeter.

Another aspect of the present invention is a measurement apparatuscomprising a portable portion having a sensor port, a processor, adisplay, and a docking connector. The sensor port is configured toreceive an intensity signal responsive to the oxygen content of arterialblood at a tissue site. The processor is programmed to compute an oxygensaturation value based upon the intensity signal and to output the valueto the display. A docking station has a portable connector and isconfigured to accommodate the portable so that the docking connectormates with the portable connector. This provides electrical connectivitybetween the docking station and the portable. The portable has anundocked position separate from the docking station in which theportable functions as a handheld pulse oximeter. The portable also has adocked position at least partially retained within the docking stationin which the combination of the portable and the docking station has atleast one additional function compared with the portable in the undockedposition.

A further aspect of the present invention is a measurement apparatusconfigured to function in both a first spatial orientation and a secondspatial orientation. The apparatus comprises a sensor port configured toreceive a signal responsive to a physiological state. The apparatus alsohas a tilt sensor providing an output responsive to gravity. Inaddition, there is a processor in communication with the sensor port andthe tilt sensor output. The processor is programmed to compute aphysiological measurement value based upon the signal and to determinewhether the measurement apparatus is in the first orientation or thesecond orientation based upon the tilt sensor output. A display has afirst mode and a second mode and is driven by the processor. The displayshows the measurement value in the first mode when the apparatus is inthe first orientation and shows the measurement value in the second modewhen the apparatus is in the second orientation.

Another aspect of the present invention is a measurement methodcomprising the steps of sensing a signal responsive to a physiologicalstate and computing physiological measurement based on the signal.Additional steps are determining the spatial orientation of a tiltsensor and displaying the physiological measurement in a mode that isbased upon the determining step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a prior art pulse oximeter;

FIG. 2 is a diagram illustrating a patient monitoring systemincorporating a universal/upgrading pulse oximeter (UPO) according tothe present invention;

FIG. 3 is top level block diagram of a UPO embodiment;

FIG. 4 is a detailed block diagram of the waveform generator portion ofthe UPO embodiment shown in FIG. 3;

FIG. 5 is an illustration of a handheld embodiment of the UPO;

FIG. 6 is a top level block diagram of another UPO embodimentincorporating a portable pulse oximeter and a docking station;

FIG. 7 is a detailed block diagram of the portable pulse oximeterportion of FIG. 6;

FIG. 8A is an illustration of the portable pulse oximeter userinterface, including a keyboard and display;

FIGS. 8B-C are illustrations of the portable pulse oximeter displayshowing portrait and landscape modes, respectively;

FIG. 9 is a detailed block diagram of the docking station portion ofFIG. 6;

FIG. 10 is a schematic of the interface cable portion of FIG. 6;

FIG. 11A is a front view of an embodiment of a portable pulse oximeter;

FIG. 11B is a back view of a portable pulse oximeter;

FIG. 12A is a front view of an embodiment of a docking station;

FIG. 12B is a back view of a docking station;

FIG. 13 is a front view of a portable docked to a docking station; and

FIG. 14 is a block diagram of one embodiment of a local area networkinterface for a docking station.

DETAILED DESCRIPTION

FIG. 2 depicts the use of a Universal/Upgrading Pulse Oximeter (“UPO”)210 to perform patient monitoring. A pulse oximetry sensor 110 isattached to a patient (not illustrated) and provides the UPO 210 with amodulated red and IR photo-plethysmograph signal through a patient cable220. The UPO 210 computes the patient's oxygen saturation and pulse ratefrom the sensor signal and, optionally, displays the patient's oxygenstatus. The UPO 210 may incorporate an internal power source 212, suchas common alkaline batteries or a rechargeable power source. The UPO 210may also utilize an external power source 214, such as standard 110V ACcoupled with an external step-down transformer and an internal orexternal AC-to-DC converter.

In addition to providing pulse oximetry measurements, the UPO 210 alsoseparately generates a signal, which is received by a pulse oximeter 268external to the UPO 210. This signal is synthesized from the saturationcalculated by the UPO 210 such that the external pulse oximeter 268calculates the equivalent saturation and pulse rate as computed by theUPO 210. The external pulse oximeter 268 receiving the UPO signal may bea multiparameter patient monitoring system (MPMS) 260 incorporating apulse oximeter module 268, a standalone pulse oximeter instrument, orany other host instrument capable of measuring SpO₂. The MPMS 260depicted in FIG. 2 has a rack 262 containing a number of modules formonitoring such patient parameters as blood pressure, EKG, respiratorygas, and SpO₂. The measurements made by these various modules are shownon a multiparameter display 264, which is typically a video (CRT)device. The UPO 210 is connected to an existing MPMS 260 with a cable230, advantageously integrating the UPO oxygen status measurements withother MPMS measurements. This allows the UPO calculations to be shown ona unified display of important patient parameters, networked with otherpatient data, archived within electronic patient records andincorporated into alarm management, which are all MPMS functionsconvenient to the caregiver.

FIG. 3 depicts the major functions of the UPO 210, including an internalpulse oximeter 310, a waveform generator 320, a power supply 330 and anoptional display 340. Attached to the UPO 210 are a sensor 110 and anexternal pulse oximeter 260. The internal pulse oximeter 310 providesthe sensor 110 with a drive signal 312 that alternately activates thesensor's red and IR LEDs, as is well-known in the art. A correspondingdetector signal 314 is received by the internal pulse oximeter 310. Theinternal pulse oximeter 310 computes oxygen saturation, pulse rate, and,in some embodiments, other physiological parameters such as pulseoccurrence, plethysmograph features and measurement confidence. Theseparameters 318 are output to the waveform generator 320. A portion ofthese parameters may also be used to generate display drive signals 316so that patient status may be read from, for example, an LED or LCDdisplay module 340 on the UPO.

The internal pulse oximeter 310 may be a conventional pulse oximeter or,for upgrading an external pulse oximeter 260, it may be an advancedpulse oximeter capable of low perfusion and motion artifact performancenot found in conventional pulse oximeters. An advanced pulse oximeterfor use as an internal pulse oximeter 310 is described in U.S. Pat. No.5,632,272 assigned to the assignee of the present invention andincorporated herein by reference. An advanced pulse oximetry sensor foruse as the sensor 110 attached to the internal pulse oximeter 310 isdescribed in U.S. Pat. No. 5,638,818 assigned to the assignee of thepresent invention and incorporated herein by reference. Further, a lineof advanced Masimo SET® pulse oximeter OEM boards and sensors areavailable from the assignee of the present invention.

The waveform generator 320 synthesizes a waveform, such as a triangularwaveform having a sawtooth or symmetric triangle shape, that is outputas a modulated signal 324 in response to an input drive signal 322. Thedrive input 322 and modulation output 324 of the waveform generator 320are connected to the sensor port 262 of the external pulse oximeter 260.The synthesized waveform is generated in a manner such that the externalpulse oximeter 260 computes and displays a saturation and a pulse ratevalue that is equivalent to that measured by the internal pulse oximeter310 and sensor 110. In the present embodiment, the waveforms for pulseoximetry are chosen to indicate to the external pulse oximeter 260 aperfusion level of 5%. The external pulse oximeter 260, therefore,always receives a strong signal. In an alternative embodiment, theperfusion level of the waveforms synthesized for the external pulseoximeter can be set to indicate a perfusion level at or close to theperfusion level of the patient being monitored by the internal pulseoximeter 310. As an alternative to the generated waveform, a digitaldata output 326, is connected to the data port 264 of the external pulseoximeter 260. In this manner, saturation and pulse rate measurements andalso samples of the unmodulated, synthesized waveform can becommunicated directly to the external pulse oximeter 260 for display,bypassing the external pulse oximeter's signal processing functions. Themeasured plethysmograph waveform samples output from the internal pulseoximeter 310 also may be communicated through the digital data output326 to the external pulse oximeter 260.

It will be understood from the above discussion that the synthesizedwaveform is not physiological data from the patient being monitored bythe internal pulse oximeter 310, but is a waveform synthesized frompredetermined stored waveform data to cause the external pulse oximeter260 to calculate oxygen saturation and pulse rate equivalent to orgenerally equivalent (within clinical significance) to that calculatedby the internal pulse oximeter 310. The actual physiological waveformfrom the patient received by the detector is not provided to theexternal pulse oximeter 260 in the present embodiment. Indeed, thewaveform provided to the external pulse oximeter will usually notresemble the plethysmographic waveform of physiological data from thepatient being monitored by the internal pulse oximeter 260.

The cable 230 (FIG. 2) attached between the waveform generator 320 andexternal pulse oximeter 260 provides a monitor ID 328 to the UPO,allowing identification of predetermined external pulse oximetercalibration curves. For example, this cable may incorporate an encodingdevice, such as a resistor, or a memory device, such as a PROM 1010(FIG. 10) that is read by the waveform generator 320. The encodingdevice provides a value that uniquely identifies a particular type ofexternal pulse oximeter 260 having known calibration curve, LED driveand modulation signal characteristics. Although the calibration curvesof the external pulse oximeter 260 are taken into account, thewavelengths of the actual sensor 110, advantageously, are not requiredto correspond to the particular calibration curve indicated by themonitor ID 328 or otherwise assumed for the external pulse oximeter 260.That is, the wavelength of the sensor 110 attached to the internal pulseoximeter 310 is not relevant or known to the external pulse oximeter260.

FIG. 4 illustrates one embodiment of the waveform generator portion 320of the UPO 210 (FIG. 3). Although this embodiment is illustrated anddescribed as hardware, one of ordinary skill will recognize that thefunctions of the waveform generator may be implemented in software orfirmware or a combination of hardware, software and firmware. Thewaveform generator 320 performs waveform synthesis with a waveformlook-up table (“LUT”) 410, a waveform shaper 420 and a waveform splitter430. The waveform LUT 410 is advantageously a memory device, such as aROM (read only memory) that contains samples of one or more waveformportions or segments containing a single waveform. These stored waveformsegments may be as simple as a single period of a triangular waveform,having a sawtooth or symmetric triangle shape, or more complicated, suchas a simulated plethysmographic pulse having various physiologicalfeatures, for example rise time, fall time and dicrotic notch.

The waveform shaper 420 creates a continuous pulsed waveform from thewaveform segments provided by the waveform LUT 410. The waveform shaper420 has a shape parameter input 422 and an event indicator input 424that are buffered 470 from the parameters 318 output from the internalpulse oximeter 310 (FIG. 3). The shape parameter input 422 determines aparticular waveform segment in the waveform LUT 410. The chosen waveformsegment is specified by the first address transmitted to the waveformLUT 410 on the address lines 426. The selected waveform segment is sentto the waveform shaper 420 as a series of samples on the waveform datalines 412.

The event indicator input 424 specifies the occurrence of pulses in theplethysmograph waveform processed by the internal pulse oximeter 310(FIG. 3). For example, the event indicator may be a delta time from theoccurrence of a previously detected falling pulse edge or this indicatorcould be a real time or near real time indicator of the pulseoccurrence. The waveform shaper 420 accesses the waveform LUT 410 in amanner to create a corresponding delta time between pulses in thesynthesized waveform output 428. In one embodiment, the waveform shaperis clocked at a predetermined sample rate. From a known number ofsamples per stored waveform segment and the input delta time from theevent indicator, the waveform shaper 420 determines the number ofsequential addresses to skip between samples and accesses the waveformLUT 410 accordingly. This effectively “stretches” or “shrinks” theretrieved waveform segment so as to fit in the time between twoconsecutive pulses detected by the UPO.

The waveform splitter 430 creates a first waveform 432 corresponding toa first waveform (such a red wavelength) expected by the external pulseoximeter 260 (FIG. 3) and a second waveform (such as infrared) 434expected by the external pulse oximeter 260. The relative amplitudes ofthe first waveform 432 and second waveform 434 are adjusted tocorrespond to the ratio output 444 from a calibration curve LUT 440.Thus, for every value of measured oxygen saturation at the sat input442, the calibration curve LUT 440 provides a corresponding ratio output444 that results in the first waveform 432 and the second waveform 434having an amplitude ratio that will be computed by the external pulseoximeter 260 (FIG. 3) as equivalent to the oxygen saturation measured bythe internal pulse oximeter 310 (FIG. 3).

As described above, one particularly advantageous aspect of the UPO isthat the operating wavelengths of the sensor 110 (FIG. 3) are notrelevant to the operating wavelengths required by the external pulseoximeter 260 (FIG. 3), i.e. the operating wavelengths that correspond tothe calibration curve or curves utilized by the external pulse oximeter.The calibration curve LUT 440 simply permits generation of a synthesizedwaveform as expected by the external oximeter 260 (FIG. 3) based on thecalibration curve used by the external pulse oximeter 260 (FIG. 3). Thecalibration curve LUT 440 contains data about the known calibrationcurve of the external pulse oximeter 260 (FIG. 3), as specified by themonitor ID input 328. In other words, the waveform actually synthesizedis not a patient plethysmographic waveform. It is merely a storedwaveform that will cause the external pulse oximeter to calculate theproper oxygen saturation valve and pulse rate values. Although this doesnot provide a patient plethysmograph on the external pulse oximeter forthe clinician, the calculated values, which is what is actually sought,will be accurate.

A modulator 450 responds to an LED drive input 322 to generate amodulated waveform output 324 derived from the first waveform 432 andsecond waveform 434. Also, a data communication interface 460 transmitsas a digital data output 326 the data obtained from the sat 442, pulserate 462 and synthesized waveform 428 inputs.

FIG. 5 depicts a handheld UPO 500 embodiment. The handheld UPO 500 haskeypad inputs 510, an LCD display 520, an external power supply input530, an output port 540 for connection to an external pulse oximeter anda sensor input 550 at the top edge (not visible). The display 520 showsthe measured oxygen saturation 522, the measured pulse rate 524, apulsating bar 526 synchronized with pulse rate or pulse events, and aconfidence bar 528 indicating confidence in the measured values ofsaturation and pulse rate. Also shown are low battery 572 and alarmenabled 574 status indicators.

The handheld embodiment described in connection with FIG. 5 may alsoadvantageously function in conjunction with a docking station thatmechanically accepts, and electrically connects to, the handheld unit.The docking station may be co-located with a patient monitoring systemand connected to a corresponding SpO₂ module sensor port, external powersupply, printer and telemetry device, to name a few options. In thisconfiguration, the handheld UPO may be removed from a first dockingstation at one location to accompany and continuously monitor a patientduring transport to a second location. The handheld UPO can then beconveniently placed into a second docking station upon arrival at thesecond location, where the UPO measurements are displayed on the patientmonitoring system at that location.

FIG. 6 shows a block diagram of a UPO embodiment, where the functions ofthe UPO 210 are split between a portable pulse oximeter 610 and adocking station 660. The portable pulse oximeter 610 (“portable”) is abattery operated, fully functional, stand-alone pulse oximeterinstrument. The portable 610 connects to a sensor 110 (FIG. 2) through aUPO patient cable 220 (FIG. 2) attached to a patient cable connector618. The portable 610 provides the sensor 110 with a drive signal 612that alternately activates the sensor's red and IR LEDs, as iswell-known in the art. The portable also receives a correspondingdetector signal 614 from the sensor. The portable can also input asensor ID on the drive signal line 612, as described in U.S. Pat. No.5,758,644 entitled Manual and Automatic Probe Calibration, assigned tothe assignee of the present invention and incorporated herein byreference.

The portable 610 can be installed into the docking station 660 to expandits functionality. When installed, the portable 610 can receive power662 from the docking station 660 if the docking station 660 is connectedto external power 668. Alternately, with no external power 668 to thedocking station 660, the portable 610 can supply power 662 to thedocking station 660. The portable 610 communicates to the dockingstation with a bi-directional serial data line 664. In particular, theportable 610 provides the docking station with SpO₂, pulse rate andrelated parameters computed from the sensor detector signal 614. Whenthe portable 610 is installed, the docking station 660 may drive a hostinstrument 260 (FIG. 2) external to the portable 610. Alternatively, theportable 610 and docking station 660 combination may function as astandalone pulse oximeter instrument, as described below with respect toFIG. 13.

In one embodiment, the docking station 660 does not perform any actionwhen the portable 610 is not docked. The user interface for the dockingstation 660, i.e. keypad and display, is on the portable 610. Anindicator LED on the docking station 660 is lit when the portable isdocked. The docking station 660 generates a detector signal output 674to the host instrument 260 (FIG. 2) in response to LED drive signals 672from the host instrument and SpO₂ values and related parameters receivedfrom the portable 610. The docking station 660 also provides a serialdata output 682, a nurse call 684 and an analog output 688.

An interface cable 690 connects the docking station 660 to the hostinstrument patient cable 230 (FIG. 2). The LED drive signals 672 anddetector signal output 674 are communicated between the docking station660 and the host instrument 260 (FIG. 2) via the interface cable 690.The interface cable 690 provides a sync data output 692 to the dockingstation 660, communicating sensor, host instrument (e.g. monitor ID 328,FIG. 3) and calibration curve data. Advantageously, this data allows thedocking station 660 to appear to a particular host instrument as aparticular sensor providing patient measurements.

FIG. 7 provides further detail of the portable 610. The portablecomponents include a pulse oximeter processor 710, a managementprocessor 720, a power supply 730, a display 740 and a keypad 750. Thepulse oximeter processor 710 functions as an internal pulse oximeter,interfacing the portable to a sensor 110 (FIG. 2) and deriving SpO₂,pulse rate, a plethysmograph and a pulse indicator. An advanced pulseoximeter for use as the pulse oximeter processor 710 is described inU.S. Pat. No. 5,632,272, referenced above. An advanced pulse oximetrysensor for use as the sensor 110 (FIG. 2) attached to the pulse oximeterprocessor 710 is described in U.S. Pat. No. 5,638,818, also referencedabove. Further, a line of advanced Masimo SET® pulse oximeter OEM boardsand sensors are available from the assignee of the present invention. Inone embodiment, the pulse oximeter processor 710 is the Masimo SET®MS-3L board or a low power MS-5 board.

The management processor 720 controls the various functions of theportable 610, including asynchronous serial data communications 724 withthe pulse oximeter processor 710 and synchronous serial communications762 with the docking station 660 (FIG. 6). The physical and electricalconnection to the docking station 660 (FIG. 6) is via a docking stationconnector 763 and the docking station interface 760, respectively. Theprocessor 720 utilizes a real-time clock 702 to keep the current dateand time, which includes time and date information that is stored alongwith SpO₂ parameters to create trend data. The processor of the portable610 and the docking station 660 (FIG. 6) can be from the same family toshare common routines and minimize code development time.

The processor 720 also controls the user interface 800 (FIG. 8A) bytransferring data 742 to the display 740, including display updates andvisual alarms, and by interpreting keystroke data 752 from the keypad750. The processor 720 generates various alarm signals, when required,via an enable signal 728, which controls a speaker driver 770. Thespeaker driver 770 actuates a speaker 772, which provides audibleindications such as, for example, alarms and pulse beeps. The processor720 also monitors system status, which includes battery status 736,indicating battery levels, and docked status 764, indicating whether theportable 610 is connected to the docking station 660 (FIG. 6). When theportable 610 is docked and is on, the processor 720 also decides when toturn on or off docking station power 732.

Advantageously, the caregiver can set (i.e. configure or program) thebehavior of the portable display 740 and alarms when the docked portable610 senses that an interface cable 690 has connected the docking station660 to an external pulse oximeter, such as a multiparameter patientmonitoring system. In one user setting, for example, the portabledisplay 740 stops showing the SpO₂ 811 (FIG. 8) and pulse rate 813 (FIG.8) values when connected to an external pulse oximeter to avoidconfusing the caregiver, who can read equivalent values on the patientmonitoring system. The display 740, however, continues to show theplethysmograph 815 (FIG. 8) and visual pulse indicator 817 (FIG. 8)waveforms. For one such user setting, the portable alarms remain active.

Another task of the processor 720 includes maintenance of a watchdogfunction. The watchdog 780 monitors processor status on the watchdogdata input 782 and asserts the μP reset output 784 if a fault isdetected. This resets the management processor 720, and the fault isindicated with audible and visual alarms.

The portable 610 gets its power from batteries in the power supply 730or from power 766 supplied from the docking station 660 (FIG. 6) via thedocking station interface 760. A power manager 790 monitors the on/offswitch on the keypad 750 and turns-on the portable power accordingly.The power manager 790 turns off the portable on command by the processor720. DC/DC converters within the power supply 730 generate the requiredvoltages 738 for operation of the portable 610 and docking station power732. The portable batteries can be either alkaline rechargeablebatteries or another renewable power source. The batteries of the powersupply 730 supply docking station power 732 when the docking station 660(FIG. 6) is without external power. A battery charger within the dockingstation power supply provides charging current 768 to rechargeablebatteries within the power supply 730. The docking station power supply990 (FIG. 9) monitors temperature 734 from a thermistor in therechargeable battery pack, providing an indication of battery chargestatus.

A non-volatile memory 706 is connected to the management processor 720via a high-speed bus 722. In the present embodiment, the memory 706 isan erasable and field re-programmable device used to store boot data,manufacturing serial numbers, diagnostic failure history, adult SpO₂ andpulse rate alarm limits, neonate SpO₂ and pulse rate alarm limits, SpO₂and pulse rate trend data, and program data. Other types of non-volatilememory are well known. The SpO₂ and pulse rate alarm limits, as well asSpO₂ related algorithm parameters, may be automatically selected basedon the type of sensor 110 (FIG. 2), adult or neonate, connected to theportable 610.

The LCD display 740 employs LEDs for a backlight to increase itscontrast ratio and viewing distance when in a dark environment. Theintensity of the backlight is determined by the power source for theportable 610. When the portable 610 is powered by either a battery packwithin its power supply 730 or a battery pack in the docking stationpower supply 990 (FIG. 9), the backlight intensity is at a minimumlevel. When the portable 610 is powered by external power 668 (FIG. 6),the backlight is at a higher intensity to increase viewing distance andangle. In one embodiment, button on the portable permits overridingthese intensity settings, and provides adjustment of the intensity. Thebacklight is controlled in two ways. Whenever any key is pressed, thebacklight is illuminated for a fixed number of seconds and then turnsoff, except when the portable is docked and derives power from anexternal source. In that case, the backlight is normally on unlessdeactivated with a key on the portable 610.

FIG. 8A illustrates the portable user interface 800, which includes adisplay 740 and a keypad 750. In one embodiment, the display 740 is adot matrix LCD device having 160 pixels by 480 pixels. The display 740can be shown in portrait mode, illustrated in FIG. 8B, or in landscapemode, illustrated in FIG. 8C. A tilt sensor 950 (FIG. 9) in the dockingstation 660 (FIG. 6) or a display mode key on the portable 610 (FIG. 6)determines portrait or landscape mode. The tilt sensor 950 (FIG. 9) canbe a gravity-activated switch or other device responsive to orientationand can be alternatively located in the portable 610 (FIG. 6). In aparticular embodiment, the tilt sensor 950 (FIG. 9) is a non-mercurytilt switch, part number CW 1300-1, available from Comus International,Nutley, N.J. (www.comusintl.com). The tilt sensor 950 (FIG. 9) couldalso be a mercury tilt switch.

Examples of how the display area can be used to display SpO₂ 811, pulserate 813, a plethysmographic waveform 815, a visual pulse indicator 817and soft key icons 820 in portrait and landscape mode are shown in FIGS.8B and 8C, respectively. The software program of the managementprocessor 720 (FIG. 7) can be easily changed to modify the category,layout and size of the display information shown in FIGS. 8B-C. Otheradvantageous information for display is SpO₂ limits, alarm, alarmdisabled, exception messages and battery status.

The keypad 750 includes soft keys 870 and fixed keys 880. The fixed keys880 each have a fixed function. The soft keys 870 each have a functionthat is programmable and indicated by one of the soft key icons 820located next to the soft keys 870. That is, a particular one of the softkey icons 820 is in proximity to a particular one of the soft keys 870and has a text or a shape that suggests the function of that particularone of the soft keys 870. In one embodiment, the button portion of eachkey of the keypad 750 is constructed of florescent material so that thekeys 870, 880 are readily visible in the dark.

In one embodiment, the keypad 750 has one row of four soft keys 870 andone row of three fixed keys 880. Other configurations are, of course,available, and specific arrangement is not significant. The functions ofthe three fixed keys 880 are power, alarm silence and light/contrast.The power function is an on/off toggle button. The alarm silencefunction and the light/contrast function have dual purposes depending onthe duration of the key press. A momentary press of the keycorresponding to the alarm silence function will disable the audiblealarm for a fixed period of time. To disable the audible alarmindefinitely, the key corresponding to the alarm silence function isheld down for a specified length of time. If the key corresponding tothe alarm silence function is pressed while the audible alarm has beensilenced, the audible alarm is reactivated. If the key corresponding tothe light/contrast function is pressed momentarily, it is an on/offtoggle button for the backlight. If the key corresponding to thelight/contrast function is held down, the display contrast cyclesthrough its possible values.

In this embodiment, the default functions of the four soft keys 870 arepulse beep up volume, pulse beep down volume, menu select, and displaymode. These functions are indicated on the display by the up arrow, downarrow, “menu” and curved arrow soft key icons 820, respectively. The upvolume and down volume functions increase or decrease the audible soundor “beep” associated with each detected pulse. The display mode functionrotates the display 740 through all four orthogonal orientations,including portrait mode (FIG. 8B) and landscape mode (FIG. 8C), witheach press of the corresponding key. The menu select function allows thefunctionality of the soft keys 870 to change from the default functionsdescribed above. Examples of additional soft key functions that can beselected using this menu feature are set SpO₂ high/low limit, set pulserate high/low limit, set alarm volume levels, set display to show trenddata, print trend data, erase trend data, set averaging time, setsensitivity mode, perform synchronization, perform rechargeable batterymaintenance (deep discharge/recharge to remove battery memory), anddisplay product version number.

FIG. 9 provides further details of the docking station 660, whichincludes a docking station processor 910, a non-volatile memory 920, awaveform generator 930, a PROM interface 940, a tilt sensor 950, aportable interface 970 and associated connector 972, status indicators982, a serial data port 682, a nurse call output 684, an analog output688 and a power supply 990. In one embodiment, the docking station 660is intended to be associated with a fixed (non-transportable) hostinstrument, such as a multiparameter patient monitoring instrument in ahospital emergency room. In a transportable embodiment, the dockingstation 660 is movable, and includes a battery pack within the powersupply 990.

The docking station processor 910 orchestrates the activity on thedocking station 660. The processor 910 provides the waveform generator930 with parameters 932 as discussed above for FIGS. 3 and 4. Theprocessor 910 also provides asynchronous serial data 912 forcommunications with external devices and synchronous serial data 971 forcommunications with the portable 610 (FIG. 6). In addition, theprocessor 910 determines system status including sync status 942, tiltstatus 952 and power status 992. The portable management processor 720(FIG. 7) performs the watchdog function for the docking stationprocessor 910. The docking station processor 910 sends watchdog messagesto the portable processor 720 (FIG. 7) as part of the synchronous serialdata 972 to ensure the correct operation of the docking stationprocessor 910.

The docking station processor 910 accesses non-volatile memory 920 overa high-speed bus 922. The non-volatile memory 920 is re-programmable andcontains program data for the processor 910 including instrumentcommunication protocols, synchronization information, a boot image,manufacturing history and diagnostic failure history.

The waveform generator 930 generates a synthesized waveform that aconventional pulse oximeter can process to calculate SpO₂ and pulse ratevalues or exception messages, as described above with respect to FIG. 4.However, in the present embodiment, as explained above, the waveformgenerator output does not reflect a physiological waveform. It is merelya waveform constructed to cause the external pulse oximeter to calculatethe correct saturation and pulse rate. In an alternative embodiment,physiological data could be provided to the external pulse oximeter, butthe external pulse oximeter would generally not be able to calculate theproper saturation values, and the upgrading feature would be lost. Thewaveform generator 930 is enabled if an interface cable 690 (FIG. 6),described below with respect to FIG. 10, with valid synchronizationinformation is connected. Otherwise, the power to the waveform generator930 is disabled.

The status indicators 982 are a set of LEDs on the front of the dockingstation 660 used to indicate various conditions including external power(AC), portable docked, portable battery charging, docking stationbattery charging and alarm. The serial data port 682 is used tointerface with either a computer, a serial port of conventional pulseoximeters or serial printers via a standard RS-232 DB-9 connector 962.This port 682 can output trend memory, SpO₂ and pulse rate and supportthe system protocols of various manufacturers. The analog output 688 isused to interface with analog input chart recorders via a connector 964and can output “real-time” or trend SpO₂ and pulse rate data. The nursecall output 684 from a connector 964 is activated when alarm limits areexceeded for a predetermined number of consecutive seconds. In anotherembodiment, data, including alarms, could be routed to any number ofcommunications ports, and even over the Internet, to permit remote useof the upgrading pulse oximeter.

The PROM interface 940 accesses synchronization data 692 from the PROM1010 (FIG. 10) in the interface cable 690 (FIGS. 6, 10) and providessynchronization status 942 to the docking station processor 910. Theportable interface 970 provides the interconnection to the portable 610(FIG. 6) through the docking station interface 760 (FIG. 7).

As shown in FIG. 9, external power 668 is provided to the dockingstation 660 through a standard AC connector 968 and on/off switch 969.When the docking station 660 has external power 668, the power supply990 charges the battery in the portable power supply 730 (FIG. 7) andthe battery, if any, in the docking station power supply 990. When theportable 610 (FIG. 6) is either removed or turned off, the dockingstation power 973 is removed and the docking station 660 is turned off,except for the battery charger portion of the power supply 990. Thedocking station power 973 and, hence, the docking station 660 turn onwhenever a docked portable 610 (FIG. 6) is turned on. The portable 610(FIG. 6) supplies power for an embodiment of the docking station 660without a battery when external power 668 is removed or fails.

FIG. 10 provides further detail regarding the interface cable 690 usedto connect between the docking station 660 (FIG. 6) and the patientcable 230 (FIG. 2) of a host instrument 260 (FIG. 2). The interfacecable 690 is configured to interface to a specific host instrument andto appear to the host instrument as a specific sensor. A PROM 1010 builtinto the interface cable 690 contains information identifying a sensortype, a specific host instrument, and the calibration curve of thespecific host instrument. The PROM information can be read by thedocking station 660 (FIG. 6) as synchronization data 692.Advantageously, the synchronization data 692 allows the docking station660 (FIG. 6) to generate a waveform to the host instrument that causesthe host instrument to display SpO₂ values equivalent to thosecalculated by the portable 610 (FIG. 6). The interface cable 690includes an LED drive path 672. In the embodiment shown in FIG. 10, theLED drive path 672 is configured for common anode LEDs and includes IRcathode, red cathode and common anode signals. The interface cable 690also includes a detector drive path 674, including detector anode anddetector cathode signals.

A menu option on the portable 610 (FIG. 6) also allows synchronizationinformation to be calculated in the field. With manual synchronization,the docking station 660 (FIG. 6) generates a waveform to the hostinstrument 260 (FIG. 2) and displays an expected SpO₂ value. The userenters the SpO₂ value displayed on the host instrument using theportable keypad 750 (FIG. 7). These steps are repeated until apredetermined number of data points are entered and the SpO₂ valuesdisplayed by the portable and the host instrument are consistent.

FIGS. 11A-B depict an embodiment of the portable 610, as described abovewith respect to FIG. 6. FIGS. 12A-B depict an embodiment of the dockingstation 660, as described above with respect to FIG. 6. FIG. 13 depictsan embodiment of the UPO 210 where the portable 610 is docked with thedocking station 660, also as described above with respect to FIG. 6.

FIG. 11A depicts the portable front panel 1110. The portable 610 has apatient cable connector 618, as described above with respect to FIG. 6.Advantageously, the connector 618 is rotatably mounted so as to minimizestress on an attached patient cable (not shown). In one embodiment, theconnector 618 can freely swivel between a plane parallel to the frontpanel 1110 and a plane parallel to the side panel 1130. In anotherembodiment, the connector 618 can swivel between, and be releasablyretained in, three locked positions. A first locked position is asshown, where the connector is in a plane parallel to the front panel1110. A second locked position is where the connector 618 is in a planeparallel to the side panel 1130. The connector 618 also has anintermediate locked position 45° between the first and the second lockedpositions. The connector 618 is placed in the first locked position forattachment to the docking station 660.

Shown in FIG. 11A, the portable front panel 1110 also has a speaker 772,as described with respect to FIG. 7. Further, the front panel 1110 has arow of soft keys 870 and fixed keys 880, as described above with respectto FIG. 8. In addition, the front panel 1110 has a finger actuated latch1120 that locks onto a corresponding catch 1244 (FIG. 12A) in thedocking station 660, allowing the portable 610 to be releasably retainedby the docking station 660. An OEM label can be affixed to a recessedarea 1112 on the front panel 1110.

FIG. 11B depicts the portable back panel 1140. The back panel 1140 has asocket 763, a pole clamp mating surface 1160, and a battery packcompartment 1170. The socket 763 is configured to mate with acorresponding docking station plug 972 (FIG. 12A). The socket 763 andplug 972 (FIG. 12A) provide the electrical connection interface betweenthe portable 610 and the docking station 660 (FIG. 12A). The socket 763houses multiple spring contacts that compress against platededge-connector portions of the docking station plug 972 (FIG. 12A). Aconventional pole clamp (not shown) may be removably attached to themating surface 1160. This conveniently allows the portable 610 to beheld to various patient-side or bedside mounts for hands-free pulseoximetry monitoring. The portable power supply 730 (FIG. 7) is containedwithin the battery pack compartment 1170. The compartment 1170 has aremovable cover 1172 for protection, insertion and removal of theportable battery pack. Product labels, such as a serial numberidentifying a particular portable, can be affixed with the back panelindent 1142.

FIG. 12A depicts the front side 1210 of the docking station 660. Thefront side 1210 has a docking compartment 1220, a pole clamp recess1230, pivots 1242, a catch 1244, a plug connector 972 and LED statusindicators 982. The docking compartment 1220 accepts and retains theportable 610 (FIGS. 11A-B), as shown in FIG. 13. When the portable 610(FIGS. 11A-B) is docked in the compartment 1220, the pole clamp recess1230 accommodates a pole clamp (not shown) attached to the portable'spole clamp mating surface 1160 (FIG. 11B), assuming the pole clamp is inits closed position. The portable 610 (FIGS. 11A-B) is retained in thecompartment 1220 by pivots 1242 that fit into corresponding holes in theportable's side face 1130 and a catch 1244 that engages the portable'slatch 1120 (FIG. 11A). Thus, the portable 610 (FIGS. 11A-B) is docked byfirst attaching it at one end to the pivots 1242, then rotating it aboutthe pivots 1242 into the compartment 1220, where it is latched in placeon the catch 1244. The portable 610 (FIGS. 11A-B) is undocked in reverseorder, by first pressing the latch 1120 (FIG. 11A), which releases theportable from the catch 1244, rotating the portable 610 (FIGS. 11A-B)about the pivots 1242 out of the compartment 1220 and then removing itfrom the pivots 1242. As the portable is rotated into the compartment,the docking station plug 972 inserts into the portable socket 763 (FIG.11B), providing the electrical interface between the portable 610 andthe docking station 660. The status indicators 982 are as describedabove with respect to FIG. 9.

FIG. 12B depicts the back side 1260 of the docking station 660. The backside 1260 has a serial (RS-232 or USB) connector 962, an analog outputand nurse call connector 964, an upgrade port connector 966, an AC powerplug 968, an on/off switch 969 and a ground lug 1162. A handle 1180 isprovided at one end and fan vents 1170 are provided at the opposite end.A pair of feet 1190 are visible near the back side 1260. A correspondingpair of feet (not visible) are located near the front side 1210 (FIG.12A). The feet near the front side 1210 extend so as to tilt the frontside 1210 (FIG. 12A) upward, making the display 740 (FIG. 13) of adocked portable 610 (FIG. 13) easier to read.

FIG. 13 illustrates both the portable 610 and the docking station 660.The portable 610 and docking station 660 constitute three distinct pulseoximetry instruments. First, the portable 610 by itself, as depicted inFIGS. 11A-B, is a handheld pulse oximeter applicable to various patientmonitoring tasks requiring battery power or significant mobility, suchas ambulance and ER situations. Second, the portable 610 docked in thedocking station 660, as depicted in FIG. 13, is a standalone pulseoximeter applicable to a wide-range of typical patient monitoringsituations from hospital room to the operating room. Third, the portable610 docked and the upgrade port 966 (FIG. 12B) connected with aninterface cable to the sensor port of a conventional pulse oximetermodule 268 (FIG. 2) within a multiparameter patient monitoringinstrument 260 (FIG. 2) or other conventional pulse oximeter, is auniversal/upgrading pulse oximeter (UPO) instrument 210, as describedherein. Thus, the portable 610 and docking station 660 configuration ofthe UPO 210 advantageously provides a three-in-one pulse oximetryinstrument functionality.

Another embodiment of the docking station 660 incorporates an input portthat connects to a blood pressure sensor and an output port thatconnects to the blood pressure sensor port of a multiparameter patientmonitoring system (MPMS). The docking station 660 incorporates a signalprocessor that computes a blood pressure measurement based upon an inputfrom the blood pressure sensor. The docking station 660 alsoincorporates a waveform generator connected to the output port thatproduces a synthesized waveform based upon the computed measurement. Thewaveform generator output is adjustable so that the blood pressure valuedisplayed on the MPMS is equivalent to the computed blood pressuremeasurement. Further, when the portable 610 is docked in the dockingstation 660 and the blood pressure sensor is connected to the inputport, the portable displays a blood pressure value according to thecomputed blood pressure measurement. Thus, in this embodiment, thedocking station 660 provides universal/upgrading capability for bothblood pressure and SpO₂.

Likewise, the docking station 660 can function as an universal/upgradinginstrument for other vital sign measurements, such as respiratory rate,EKG or EEG. For this embodiment, the docking station 660 incorporatesrelated sensor connectors and associated sensor signal processors andupgrade connectors to an MPMS or standalone instrument. In this manner,a variety of vital sign measurements can be incorporated into thedocking station 660, either individually or in combination, with orwithout SpO₂ as a measurement parameter, and with or without theportable 610. In yet another embodiment, the docking station 660 can beconfigured as a simple SpO₂ upgrade box, incorporating a SpO₂ processorand patient cable connector for a SpO₂ sensor that functions with orwithout the portable 610.

Unlike a conventional standalone pulse oximeter, the standaloneconfiguration shown in FIG. 13 has a rotatable display 740 that allowsthe instrument to be operated in either a vertical or horizontalorientation. A tilt sensor 950 (FIG. 9) indicates when the bottom face1310 is placed along a horizontal surface or is otherwisehorizontally-oriented. In this horizontal orientation, the display 740appears in landscape mode (FIG. 8C). The tilt sensor 950 (FIG. 9) alsoindicates when the side face 1320 is placed along a horizontal surfaceor is otherwise horizontally oriented. In this vertical orientation, thedisplay 740 appears in portrait mode (FIG. 8B). A soft key 870 on theportable 610 can override the tilt sensor, allowing the display to bepresented at any 90° orientation, i.e. portrait, landscape,“upside-down” portrait or “upside-down” landscape orientations. Thehandheld configuration (FIG. 11A), can also present the display 740 atany 90° orientation using a soft key 870. In the particular embodimentdescribed above, however, the portable 610 does not have a tilt sensorand, hence, relies on a soft key 870 to change the orientation of thedisplay when not docked.

FIG. 14 illustrates the docking station 660 incorporated within a localarea network (LAN). The LAN shown is Ethernet-based 1460, using acentral LAN server 1420 to interconnect various LAN clients 1430 andother system resources such as printers and storage (not shown). AnEthernet controller module 1410 is incorporated with the docking station660. The controller module 1410 can be incorporated within the dockingstation 660 housing or constructed as an external unit. In this manner,the UPO, according to the present invention, can communicate with otherdevices on the LAN or over the Internet 1490.

The Ethernet controller module 1410 can be embedded with web serverfirmware, such as the Hewlett-Packard (HP) BFOOT-10501. The module 1410has both a 10 Base-T Ethernet interface for connection to the Ethernet1460 and a serial interface, such as RS-232 or USB, for connection tothe docking station 660. The module firmware incorporates HTTP andTCP/IP protocols for standard communications over the World Wide Web.The firmware also incorporates a micro web server that allows custom webpages to be served to remote clients over the Internet, for example.Custom C++ programming allows expanded capabilities such as datareduction, event detection and dynamic web page configuration.

As shown in FIG. 14, there are many applications for the docking station660 to Ethernet interface. Multiple UPOs can be connected to ahospital's LAN, and a computer on the LAN could be utilized to uploadpulse rate and saturation data from the various UPOs, displaying theresults. Thus, this Ethernet interface could be used to implement acentral pulse oximetry monitoring station within a hospital. Further,multiple UPOs from anywhere in the world can be monitored from a centrallocation via the Internet. Each UPO is addressable as an individual website and downloads web pages viewable on a standard browser, the webpages displaying oxygen saturation, pulse rate and related physiologicalmeasurements from the UPO. This feature allows a caregiver to monitor apatient regardless of where the patient or caregiver is located. Forexample a caregiver located at home in one city or at a particularhospital could download measurements from a patient located at home in adifferent city or at the same or a different hospital. Otherapplications include troubleshooting newly installed UPOs or uploadingsoftware patches or upgrades to UPOs via the Internet. In additionalarms could be forwarded to the URL of the clinician monitoring thepatient.

The UPO may have other configurations besides the handheld unitdescribed in connection with FIG. 5 or the portable 610 and dockingstation 660 combination described in connection with FIGS. 11-13. TheUPO may be a module, with or without a display, that can be removablyfastened to a patient via an arm strap, necklace or similar means. In asmaller embodiment, this UPO module may be integrated into a cable orconnector used for attaching a sensor to a pulse oximeter. The UPO mayalso be a circuit card or module that can externally or internally pluginto or mate with a standalone pulse oximeter or multiparameter patientmonitoring system. Alternatively, the UPO may be configured as a simplestandalone upgrade instrument.

Further, although a universal/upgrading apparatus and method have beenmainly described in terms of a pulse oximetry measurement embodiment,the present invention is equally applicable to other physiologicalmeasurement parameters such as blood pressure, respiration rate, EEG andECG, to name a few. In addition, a universal/upgrading instrument havinga single physiological measurement parameter or a multiple measurementparameter capability and configured as a handheld, standalone, portable,docking station, module, plug-in, circuit card, to name a few, is alsowithin the scope of the present invention.

The UPO has been disclosed in detail in connection with variousembodiments of the present invention. These embodiments are disclosed byway of examples only and are not to limit the scope of the presentinvention, which is defined by the claims that follow. One of ordinaryskill in the art will appreciate many variations and modificationswithin the scope of this invention.

1. A method for communicating a physiological waveform indicative of aphysiological condition to a patient monitoring device, the methodcomprising: obtaining a sensor signal indicative of a physiologicalparameter; calculating a first physiological measurement using a firstprocessor; communicating the physiological measurement to a secondprocessor; outputting a physiological sensor signal from the secondprocessor based on the calculated first physiological measurement; andcommunicating the outputted physiological sensor signal to a patientmonitoring device not associated with the first and second processors,the outputted physiological sensor signal configured to cause thepatient monitoring device to calculate a second physiologicalmeasurement substantially equivalent to the first physiologicalmeasurement.
 2. The method of claim 1, further comprising displaying thecalculated first physiological measurement on a first display associatedwith the first processor.
 3. The method of claim 1, wherein thephysiological measurements comprise at least one of blood oxygen levels,blood pressure, ECG, and pulse rate.
 4. The method of claim 1, whereinthe second processor comprises a waveform generator.
 5. The method ofclaim 1, wherein the second processor is housed within a dockingstation.
 6. A system for communicating a physiological waveformindicative of a physiological condition to a patient monitoring device,the system comprising: a sensor input configured to obtain a sensorsignal indicative of a physiological parameter; one or more processorsconfigured to calculate a first physiological measurement and furtherconfigured to output a physiological signal based on the firstphysiological measurement; and an output configured to communicate thephysiological signal to a patient monitoring device not associated withthe one or more processors, the physiological signal configured to causethe patent monitoring device to calculate a second physiologicalmeasurement substantially equivalent to the first physiologicalmeasurement.
 7. The method of claim 6, further comprising a firstdisplay in communication with the one or more processors, wherein thedisplay is configured to display the calculated first physiologicalmeasurement.
 8. The method of claim 6, wherein the physiologicalmeasurements comprise at least one of blood oxygen levels, bloodpressure, ECG, and pulse rate.
 9. A method for communicating aphysiological waveform indicative of a physiological condition to apatient monitoring device, the method comprising: obtaining a firstsensor signal indicative of a physiological parameter; calculating afirst physiological measurement based on the first sensor signal;outputting a second sensor signal based on the first physiologicalmeasurement; and communicating the second sensor signal to a patientmonitoring device, the second sensor signal configured to cause thepatient monitoring device to calculate a second physiologicalmeasurement substantially equivalent to the first physiologicalmeasurement; wherein the patient monitoring device communicates with asecond display.
 10. The method of claim 9, further comprising displayinga power on indication on a first display.
 11. The method of claim 9,further comprising displaying signal quality information on a firstdisplay.
 12. The method of claim 9, further comprising displaying thefirst physiological measurement on a first display.
 13. A system forcommunicating a physiological waveform indicative of a physiologicalcondition to a patient monitoring device, the system comprising: asensor input configured to obtain a first sensor signal indicative of aphysiological parameter; at least one processor configured to determinea first physiological measurement based on the first sensor signal andoutput a second sensor signal based on the first sensor signal; and anoutput configured to communicate the second sensor signal to a patientmonitoring device, the second sensor signal configured to be used by thepatient monitoring device to calculate a second physiologicalmeasurement substantially equivalent to the first physiologicalmeasurement, wherein the patient monitoring device communicates with asecond display.
 14. The system of claim 13, further comprising a firstdisplay.